Extended Learning Module E NETWORK BASICS

1. Extended Learning Module ENETWORK BASICS

2. STUDENT LEARNING OUTCOMES • Identify and describe the four basic concepts on which networks are built and describe what is needed to set up a small peer-to-peer network at home. • Describe the components used to build large business networks and define and compare local area networks (LANs), wide area networks (WANs), and metropolitan area networks (MANs).

3. STUDENT LEARNING OUTCOMES • Compare and contrast the various Internet connection possibilities. • Compare and contrast the types of communications media.

4. STUDENT LEARNING OUTCOMES • State the four principles of computer security and describe how different network security devices reflect those principles. • Describe client/server business networks from a business and physical point of view.

5. INTRODUCTION • Computer network – two or more computers connected so that they can communicate with each other and share information, software, peripheral devices, and/or processing power

6. INTRODUCTION

7. Basic Principles of Networks • Four main principles • Each computer must have a network interface to provide a doorway for information • The network usually has at least one connecting device • The network must have communications media to transport information

8. Basic Principles of Networks • Each computer must have software to move information in and out of the computer • These four principles apply to all networks, large and small

9. HOME NETWORKS • A typical home network setup has • An Ethernet network card in each computer or a wireless card in each laptop • Network cables to transmit signals, or no cables for wireless • A DSL or cable modem connection and a broadband/home router

10. Network Cards • Network interface card (NIC) – an expansion card or PC card that connects your computer to a network • Ethernet card – the most common type of network interface card • Built into the motherboards of many new computers – looks like a telephone jack, but wider

11. Wired Transmission Media • Cat 5 (Category 5) cable – better-constructed version of phone twisted-pair cable

12. Wireless Transmission Media • Wireless Access Point (WAP) – device that allows a computer to use radio waves to access a network • Connects to hub or switch with a cable like a wired computer • May be built into broadband router and not require separate cabling

13. Home Internet Service • Broadband router or home router – a device to connect computers together to share DSL or cable Internet service in a home or small office • One port to plug into DSL or cable connection to connect to the Internet • Usually several ports to build a network for home computers or printers and share Internet connection

14. Network Software • Makes each computer's hardware work • Can use Windows • Turn on filesharing to make files available to other computers on the network

15. NETWORK COMPONENTS • Hub – a device that connects computers into a network and repeats all transmissions to every connected computer • Only one computer can transmit at a time • All computers see every message • Can have collisions when two computers try to transmit at the same time

16. NETWORK COMPONENTS • Switch – a device that connects computers and repeats transmissions only to intended recipient • Multiple conversations can occur simultaneously between different sets of computers • Only recipient computer sees each message • Computers can still broadcast messages to all other computers on the network

17. NETWORK COMPONENTS • Router – a device that connects subnetworks (subnets) of a larger network • Can connect different buildings at same or different locations • Passes transmissions from one network to another • May pass through multiple routers on the way from source to destination

18. NETWORK COMPONENTS • More on routers • Home/broadband routers often have built-in switches or hubs • Corporate routers generally require separate switches or hubs • Routers must be configured with information about the networks they connect

19. NETWORKS BY DISTANCE • Large networks can be classified by the proximity of the area(s) they serve: • Local Area Network (LAN) – network that serves a building or buildings in a contiguous area

20. NETWORKS BY DISTANCE • More networks by distance • Wide Area Network (WAN) – a set of connected networks serving areas not immediately contiguous • Metropolitan Area Network (MAN) – a set of connected networks within the same city or metropolitan area but not in immediate proximity to each other

21. THE INTERNET • A vast network of computers that connects people all over the world • Computers pass messages through routers to their ultimate destinations • Each router determines whether it has a direct path to the recipient or whether to send the message on to another router

22. Bandwidth • The amount of information that can be transferred in a given amount of time • Usually expressed as bits per second (bps) • Higher bandwidths expressed as • kilobits per second (Kbps) – thousands of bits per second • megabits per second (Mbps) – millions of bits per second • gigabits per second (Gbps) – billions of bits per second

23. Internet Connection Types • Phone line and dialup modem • Phone line and DSL modem • Cable TV line and cable modem • Satellite modem • Dedicated high-speed business lines

24. Broadband Internet Connection • Broadband – high-capacity telecommunications line capable of providing high-speed Internet service • All Internet access methods on the previous slide are broadband except the dialup modem

25. Dialup Connection • Modem – connects a computer to a phone line to access another computer or network • Modulates outgoing signal from digital to analog form • Demodulates incoming signal from analog to digital form

26. Digital Subscriber Line (DSL) • Digital Subscriber Line (DSL) – high-speed Internet connection using phone lines, which allows you to use your phone for voice communications at the same time • Runs at a higher frequency than voice conversations, so not supported on some older phone lines

27. Cable Modem • Cable modem – uses your TV cable to deliver an Internet connection

28. Satellite Modem • Satellite modem – delivers Internet access from satellite dish • Satellite TV and modem may share same dish or may be separate • Connects to computer or broadband router like cable modem

29. T1 and DS3 Business Lines • T1 and DS3 developed by phone companies to carry many long-distance voice conversations • T1 runs up to about 1.5 Mbps • DS3 runs up to about 45 Mbps • Can carry both voice and network over the same lines

30. Frame Relay and ATM Business Services • Frame Relay and ATM are used to connect many branch offices to the main office • Use virtual circuits to simulate having a line from every office to every other office Virtual Circuits

31. Comparison of Connection Types • Telephone modem • + Inexpensive and available anywhere there's a phone line • - Slow, and ties up the line for voice calls too • DSL • + Higher-speed connection, doesn't tie up the phone line for voice calls, and can be left on all the time • - Not available in all areas or on all lines

32. Comparison of Connection Types • Cable modem • + Higher-speed connection, doesn't use the phone line at all, and always-on • - Connection shared with the neighborhood, so speed may vary • Satellite modem • + Available in remote locations where DSL and cable aren't • - High cost

33. Comparison of Connection Types • T1 and DS3 • + High-speed to very-high-speed connections, can transmit both voice and data • - High cost that may be mileage-dependent • Frame relay and ATM • + Use virtual circuits to simulate more inter-office connections than are physically present • - High cost normally affordable only by mid- to large-scale enterprises

34. Voice Over IP • Voice over IP – allows you to send voice communications over the Internet and avoid long-distance toll charges • No long-distance calling cost

35. NETWORK COMMUNICATIONS MEDIA • Communications media – the paths in a network over which information travels • Wired communications media – transmit information over a closed, connected path • Wireless communications media – transmit information through the air

36. Wired Communications Media • Twisted-pair cable – a bundle of copper wires for transmitting voice or data • Cat 5 and Cat 5e are common for modern networks • Coaxial cable (coax) – one central wire surrounded by insulation, a metallic shield, and a covering of insulation

37. Wired Communications Media • Optical fiber – uses a very thin glass or plastic fiber through which pulses of light travel

38. Wireless Communications Media • Infrared – uses red light to send and receive information • Bluetooth – a standard for transmitting information in the form of short-range radio waves over distances of up to 30 feet and is used for purposes such as wirelessly connecting a cell phone or PDA to a computer • Microwave – a type of radio transmission • Repeater – receives a radio signal, strengthens it, and sends it on

39. Wireless Communications Media

40. Wireless Communications Media • Communications Satellite – microwave repeater in space

41. NETWORK SECURITY • The four principles of network security are: • Confidentiality • Authenticity • Integrity • Availability

42. NETWORK SECURITY • Confidentiality – information can be obtained only by those authorized to access it • Bank statements, credit reports, employee evaluations • Threatened by capture of network transmissions and easily-guessed passwords

43. NETWORK SECURITY • Authenticity – information really comes from the source it claims to come from • Military orders, medical diagnoses, stockbroker directions • Threatened by fraudulent e-mails and misspellings of popular Web site names

44. NETWORK SECURITY • Integrity – information has not been altered • Bank balance, corporate Web site, prescriptions, credit card charges • Threatened by forged network transmissions and faulty server software

45. NETWORK SECURITY • Availability – a service or resource is available when it's supposed to be • Mail-order Web site, corporate e-mail server • Threatened by network failures, faulty server software, and high volumes of malicious network traffic

46. Firewalls & Intrusion Detection Systems • Firewall – protects a computer from intruders • Intrusion detection system (IDS) – watches for and reports intrusion attempts • Intrusion prevention system (IPS) – type of IDS that also takes action against intrusion attempts

47. Encryption • Encryption – scrambles data so you can't read it without having the decryption key • Virtual Private Network (VPN) – encrypts all network transmissions between two endpoints to protect confidentiality and integrity of data

48. Firewalls & Intrusion Detection Systems

49. Malware • Malware – software designed to harm your computer or security • Virus – software written with malicious intent to cause annoyance or damage • Worm – spreads itself from computer to computer via e-mail and other network traffic • Spyware – collects information about you and reports it to someone else without your permission

50. CLIENT/SERVER SOFTWARE MODEL • Client/server network – a network in which one or more computers are servers and provide services to the other computers, called clients